#include <easyx.h>

#include <atomic>
#include <chrono>
#include <cstdint>
#include <fstream>
#include <string>
#include <windows.h>

namespace
{
	constexpr UINT ProbeMessage = WM_APP + 0x41;
	std::atomic<DWORD> probeWndProcThread{ 0 };
	std::atomic<DWORD> keyWndProcThread{ 0 };
	std::atomic<unsigned int> keyWndProcCount{ 0 };
	HANDLE probeObserved = nullptr;
	WNDPROC previousWndProc = nullptr;

	LRESULT CALLBACK ProbeWndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
	{
		if (message == ProbeMessage)
		{
			probeWndProcThread.store(GetCurrentThreadId(), std::memory_order_release);
			if (probeObserved)
				SetEvent(probeObserved);
		}
		else if (message == WM_KEYDOWN || message == WM_KEYUP)
		{
			keyWndProcThread.store(GetCurrentThreadId(), std::memory_order_release);
			keyWndProcCount.fetch_add(1, std::memory_order_relaxed);
		}

		return previousWndProc
			? CallWindowProcA(previousWndProc, hwnd, message, wParam, lParam)
			: DefWindowProcA(hwnd, message, wParam, lParam);
	}

	bool postFixedKey(HWND hwnd)
	{
		constexpr LPARAM KeyDownLParam = 1 | (0x1E << 16);
		constexpr LPARAM KeyUpLParam = KeyDownLParam | (1LL << 30) | (1LL << 31);
		return PostMessageA(hwnd, WM_KEYDOWN, 'A', KeyDownLParam) != FALSE &&
			PostMessageA(hwnd, WM_KEYUP, 'A', KeyUpLParam) != FALSE;
	}
}

int main(int argc, char** argv)
{
	const std::string outputPath = argc > 1 ? argv[1] : "easyx-thread-probe.json";
	const DWORD processId = GetCurrentProcessId();
	const DWORD mainThreadBeforeInit = GetCurrentThreadId();
	HWND hwnd = initgraph(320, 180, 1);
	const DWORD mainThreadAfterInit = GetCurrentThreadId();
	DWORD windowProcessId = 0;
	const DWORD windowOwnerThread = GetWindowThreadProcessId(hwnd, &windowProcessId);
	const bool windowUnicode = IsWindowUnicode(hwnd) != FALSE;
	ShowWindow(hwnd, SW_HIDE);

	probeObserved = CreateEventW(nullptr, TRUE, FALSE, nullptr);
	SetLastError(ERROR_SUCCESS);
	previousWndProc = reinterpret_cast<WNDPROC>(
		SetWindowLongPtrA(hwnd, GWLP_WNDPROC, reinterpret_cast<LONG_PTR>(&ProbeWndProc)));
	const DWORD subclassError = previousWndProc ? ERROR_SUCCESS : GetLastError();

	bool probePosted = false;
	bool probeDelivered = false;
	bool keyPosted = false;
	DWORD peekCallerThread = 0;
	unsigned int easyxKeyCount = 0;
	if (previousWndProc && probeObserved)
	{
		probePosted = PostMessageA(hwnd, ProbeMessage, 0, 0) != FALSE;
		probeDelivered = probePosted && WaitForSingleObject(probeObserved, 5000) == WAIT_OBJECT_0;
		keyPosted = postFixedKey(hwnd);

		const auto deadline = std::chrono::steady_clock::now() + std::chrono::seconds(5);
		while (std::chrono::steady_clock::now() < deadline && easyxKeyCount < 2)
		{
			ExMessage message{};
			peekCallerThread = GetCurrentThreadId();
			if (peekmessage(&message, EX_KEY, true))
			{
				if ((message.message == WM_KEYDOWN || message.message == WM_KEYUP) &&
					message.vkcode == 'A')
				{
					++easyxKeyCount;
				}
			}
			else
			{
				Sleep(1);
			}
		}
	}

	const DWORD observedProbeThread = probeWndProcThread.load(std::memory_order_acquire);
	const DWORD observedKeyThread = keyWndProcThread.load(std::memory_order_acquire);
	const unsigned int observedKeyWndProcCount = keyWndProcCount.load(std::memory_order_relaxed);
	const bool separateWindowThread = windowOwnerThread != 0 && windowOwnerThread != mainThreadAfterInit;
	const bool wndProcMatchesOwner = observedProbeThread != 0 && observedProbeThread == windowOwnerThread;
	const bool keyCrossedBothBackends = keyPosted && observedKeyWndProcCount >= 2 && easyxKeyCount >= 2;
	const bool completed = hwnd != nullptr && previousWndProc != nullptr && probeDelivered &&
		wndProcMatchesOwner && keyCrossedBothBackends;

	{
		std::ofstream output(outputPath, std::ios::trunc);
		output << "{\n"
			<< "  \"schemaVersion\": 1,\n"
			<< "  \"processId\": " << processId << ",\n"
			<< "  \"windowProcessId\": " << windowProcessId << ",\n"
			<< "  \"mainThreadBeforeInit\": " << mainThreadBeforeInit << ",\n"
			<< "  \"mainThreadAfterInit\": " << mainThreadAfterInit << ",\n"
			<< "  \"windowOwnerThread\": " << windowOwnerThread << ",\n"
			<< "  \"probeWndProcThread\": " << observedProbeThread << ",\n"
			<< "  \"keyWndProcThread\": " << observedKeyThread << ",\n"
			<< "  \"peekCallerThread\": " << peekCallerThread << ",\n"
			<< "  \"windowUnicode\": " << (windowUnicode ? "true" : "false") << ",\n"
			<< "  \"subclassError\": " << subclassError << ",\n"
			<< "  \"probePosted\": " << (probePosted ? "true" : "false") << ",\n"
			<< "  \"probeDelivered\": " << (probeDelivered ? "true" : "false") << ",\n"
			<< "  \"keyPosted\": " << (keyPosted ? "true" : "false") << ",\n"
			<< "  \"keyWndProcCount\": " << observedKeyWndProcCount << ",\n"
			<< "  \"easyxKeyCount\": " << easyxKeyCount << ",\n"
			<< "  \"separateWindowThread\": " << (separateWindowThread ? "true" : "false") << ",\n"
			<< "  \"wndProcMatchesOwner\": " << (wndProcMatchesOwner ? "true" : "false") << ",\n"
			<< "  \"keyCrossedBothBackends\": " << (keyCrossedBothBackends ? "true" : "false") << ",\n"
			<< "  \"completed\": " << (completed ? "true" : "false") << "\n"
			<< "}\n";
	}

	if (previousWndProc)
		SetWindowLongPtrA(hwnd, GWLP_WNDPROC, reinterpret_cast<LONG_PTR>(previousWndProc));
	if (probeObserved)
		CloseHandle(probeObserved);
	closegraph();
	return completed ? 0 : 2;
}